Most auto parts suppliers list them as 1994 to 1996 for Mustang so a '94 or '95 should work too. Example at the link below.
There is an ample supply of radiators for the 1996 advertised on the web if you do a search for "1996 Mustang Radiator."
http://www.go-part.com/9496-ford-mustang-radiator-p-24119.html